• Journal of Korea Water Resources Association
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• v.38 no.5 s.154
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• pp.365-377
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• 2005

This paper presents numerical works carried out for developing an advanced computational framework for understanding injury- and mortality-inducing flow phenomena in hydropower facilities. Large-eddy simulation (LES) of a circular jet flow is carried out to help interpret the results of recent experiments that exposed live fish to the shear zone of a turbulent jet. The instantaneous flow field of LES is characterized by intense velocity, pressure, and vorticity fluctuations, which could exert forces and moments on a fish considerably larger than those exerted by the same fish exposed to the corresponding steady, time-averaged flow. In this study, also, unsteady modeling of flow in a hydroturbine draft tubewas carried out using a hybrid unsteady RANS/LES, so-called detached-eddy simulation (DES). Results from DES show that the potential for disorientation and excessive residence times of fish within the draft tube is certainly considerable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4216-4227
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• 2015

In this study, a model is developed based on Life Cycle Energy Analysis (LCEA) method with Genetic Algorithm (GA) to determine optimal diameter of Water Distribution System (WDS). For hydraulic analysis the EPANET2.0 program is linked with developed model, pipe-aging equation and pipe-breakage equation are built in to developed model to simulate pipe change through life cycle. The model is then applied to two sample WDSs for optimal energy design. After determining optimal diameter for each WDS, the total cost is calculated based on determined diameter and compared with well-known optimal diameter set of each WDS. Results show that optimal energy design of WDSs through the developed model can be an alternative option for optimal design of WDSs for reducing energy with lower in cost.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.6-6
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• 2019

상수관망시스템은 공급원으로부터 수요처까지의 용수공급을 위해 구축된 관수로 기반의 사회기반시설물로서, 주로 생활 및 산업 용수를 공급하므로 대규모 사회 경제적 피해를 방지하기 위해서는 안정적인 용수공급 능력이 요구된다. 네트워크의 다양한 특성에 의해 표현되는 상수관망시스템의 신뢰도(reliability)는 크게 시스템 내 구성요소의 안정성(mechanical reliability)과 용수공급의 기능적 안정성(hydraulic reliability)으로 구분할 수 있다. 특히, 시스템의 용수공급 안정성에 주목한 수리학적 신뢰도 연구는 많은 연구자들에 의해 지속적으로 수행된 바 있으며, 다양한 평가방법 및 지표들이 제시되어 활용 중에 있다. 기존의 수리학적 신뢰도 지표들은 주로 수요절점(demand node)에서의 공급가능 수량 및 수압을 바탕으로 산정되었다. 그러나, 절점(node)에서의 공급 상태는 결과에 해당하며, 원인 분석을 위해서는 관로(pipe)의 배치 및 규격을 분석해야 하는 번거로움이 존재한다. 이러한 단점을 보완하기 위해, 본 연구에서는 직접 관로(pipe)의 공급 특성을 분석하여 네트워크의 신뢰도를 평가함으로써, 신뢰도 저하의 원인 분석 및 시스템 개선에 효율적으로 활용할 수 있는 신뢰도 지표를 산정하고자 하였다. 본 연구에서는 상수관로 내 수리학적 기울기가 전반적으로 균등할수록 설계 비용대비 공급 신뢰도, 즉 용수공급 효율이 개선되는 특징을 바탕으로, 네트워크 내 총 에너지 손실로부터 각 관로의 길이, 유량 등의 특성을 고려한 등가 수리경사(Equivalent hydraulic gradient)를 유도하여 모든 관로의 적정 수리경사로 제안하였다. 따라서 각 관로의 실제 수리경사를 대상으로 관로별 수리학적 균등성 지수(pipe hydraulic uniformity index)를 산정하였으며, 더 나아가 전체 시스템의 균등성 지수(system hydraulic uniformity index)를 산정하였다. 제안된 신뢰도 지표는 가상의 네트워크에서 지역 내 용수 사용량이 증가하는 등 용수공급 안정성을 저해하는 몇 가지 시나리오를 바탕으로 검증하였으며, 또한 기존 지표들의 신뢰도 평가 결과와 비교, 분석하였다. 본 연구는 향후 네트워크 최적 설계의 목적함수로 활용하거나, 네트워크의 보강계획 수립에 기여할 것으로 기대된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.293-296
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• 2008

Most of the guided weapons have been kept and transferred at the launching tube and fired in case of necessity in these day. Launching tube is a kind of case to protect the guided weapons from external environments and conducted as a guide when they are fired. When we attached the guided weapons to launching tube we usually has used explosive bolt. Explosive bolts have been used explosives when they had to be separated. But when they are separated there are some bad effects; a flame, fragments and pyro-shock. Because of these bad effects there are many restriction to use bolt as joining devices to precision guided weapons. To solve these problems, it has been invented ball type bolt. The present work was represented quantitively the margin of separation safty and separation mechanism in ball type bolt to analyse the dynamic separation test. Unlike explosive bolt, ball type bolt is separated without a flame, fragments and pyro-shock. And it also has a good mechanical properties as much as those of explosive bolt.

• Journal of Life Science
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• v.31 no.11
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• pp.1037-1045
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• 2021

The prevalence of obesity is increasing worldwide, and since obesity is associated with dietary factors and sedentary lifestyles, it is a disease that is readily developing in the modern population. Because obesity is accompanied by serious complications such as diabetes and cardiovascular disease, prevention and treatment are important. Currently, drugs such as liraglutide and phentermine are used to treat obesity by suppressing appetite and inducing gastrointestinal motility delay. However, various side effects may occur, including thyroid cancer, cardiovascular problems, and central nervous system disorders. Therefore, to explore an obesity treatment method with relatively few side effects, a method known as "fat browning" was introduced to change white adipose tissue into brown adipose tissue to increase energy consumption. Ongoing studies are attempting to find effective natural substances to safely induce browning. Many natural substances have been identified. The induction of browning by treatment with natural substances generally involves three mechanisms: positive control of browning-inducing factors, inhibition of differentiation into white adipose tissue, and the activation of mechanisms related to browning. In this study, we describe plant extracts with known browning-inducing effects, such as strawberry, black raspberry, cinnamomum cassia, and Ecklonia stolonifera extracts. We also summarize the underlying mechanisms of action identified thus far, including the signaling pathway mediated by these extracts to induce browning. Furthermore, the effects of brown adipose tissue generated through browning on heart disease as an endocrine organ disruptor are discussed.

• Journal of The Korean Association For Science Education
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• v.23 no.5
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• pp.544-560
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• 2003

The purposes of this study were (1) to investigate the characteristics of the exhibits at three representative science centers or museums in Seoul, and (2) to analyse students' perceptions about the most and the least favorite exhibits selected by students as visitors. Three science centers investigated were Seoul National Science Museum, Seoul Education & Science Research Institute, LG Science Hall. The subjects for students' perception survey were 290 middle school students who visited the three science centers. The investigation of the exhibits showed that the goals, the contents, the visitors' viewing and manipulating activity types, and the explanation types of the exhibits depended on the purposes and the target visitors of each science center. Students' responses indicated that they most favored hands-on exhibit. And students preferred the exhibits that had new and comprehensible contents and the were related to what they had learned in school. Students said that they felt that science was exciting and that they came to experience what they did not do in school. Students said that reading or hearing given explanations was helpful to understand the exhibits, but about 20% of the students responded that they did not read explanation on panels at all. Students also said that guide's oral explanations were more understandable than written explanations on panels. Some of the students commented that having to wait for access because of crowds or because of the resetting time required for hands-on activities was inconvenience.

• Journal of Life Science
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• v.20 no.12
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• pp.1902-1905
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• 2010

This study was conducted to increase the efficiency of farming practice in rainbow trout, Oncorhynchus mykiss, by sex reversal and chromosome-set manipulation techniques. Induction of sex-reversed gynogenetic diploid rainbow trout males and mass production of all-female rainbow trout by genetic sex reversal was performed. Phenotypic males in the gynogenetic diploid group were induced successfully by dietary administration of 5 mg of 17 alpha-methyltestosterone per kg diet for 82 days. All females were produced by crossing between normal female and sex-reversed gynogenetic diploid male rainbow trout.

• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.167-174
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• 2016

Runway and taxiway is base facilities for aircraft take off and landing and runway capacity is one of major factor for airport capacity. Runway occupancy time is affect on the runway capacity. The identification of aircraft using taxiway by analysis of airport ground surveillance data and the measurement of pass time on the points is general method for the confirmation of the runway occupancy time. This study is runway occupancy time analysis of landing airplane using ADS-B message, in this study we surveyed landing aircraft runway occupancy time and analysis of serviced record using taxiway include rapid exit taxiway. The result of analysis is to confirm the different of landing direction and aircraft category on the same runway caused by structure of airport. Also the result of runway occupancy time analyzed data, it is base input data for the air transportation simulation.

• Journal of Acupuncture Research
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• v.27 no.5
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• pp.105-115
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• 2010

목적 : 침은 다양한 질환의 치료에 보편적으로 쓰이고 있으며 고혈압, 당뇨, 정신질환 등을 포함한 스트레스성 질환에도 활용되고 있다. 결박 스트레스는 스트레스 호르몬(코르티코스테론, 멜라토닌)의 혈장 농도를 크게 증가시키는 간단하고 효과적인 스트레스 요인이다. 본 연구는 결박 스트레스를 시행한 백서의 스트레스 호르몬의 혈중 농도에 대한 전기침의 효과를 조사하였다. 방법 : 결박 그룹은 2시간의 결박 스트레스를 받았으며 결박 스트레스 및 고주파수 전침그룹과 결박 스트레스 및 저주파수 전침그룹은 결박 스트레스와 고주파수 전침, 또는 결박 스트레스와 저주파수 전침을 동시에 각각 시행하였다. 급성 스트레스 유발 시에는 결박 스트레스를 1차례, 만성 스트레스 유발 시에는 7차례 시행하였다. 전기침 자극에는 우측 족삼리($ST_{36}$)를 사용하였다. 결박 스트레스 및 전기침으로 유도된 코르티코스테론과 멜라토닌의 농도를 측정하기 위해서 결박 스트레스 및 전기침 자극이 시작된 30분, 60분, 90분, 120분 후에 백서를 단두하여 혈액 샘플을 채취하였다. 결과 : 급성 스트레스 유발 시에는 고주파수 전침그룹의 코르티코스테론 혈장 농도가 증가하였고 멜라토닌 농도의 시간적 패턴을 변화시켰으나 저주파수 전침그룹에서는 유의한 변화가 없었다. 만성 스트레스 유발 시에는 고주파수 전침그룹의 혈장 코르티코스테론과 멜라토닌 농도가 유의하게 감소되었으나 저주파수 전침그룹에서는 변화가 없었다. 결론 : 이러한 결과는 전침이 결박 스트레스로 유도된 스트레스 호르몬의 혈장 농도 및 시간적 분비패턴을 변화시키는 효과가 있으나 스트레스 호르몬 반응을 변화시키는 데 있어서 주파수에 따른 유의한 차이가 있다는 것을 의미한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.933-935
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• 2017

This paper deals with the influence of fungi for the thermal protective cork-based exterior insulator which protect a missile system from aerodynamic loads and heating during flight of missile. We consider the adhesion of cork-based composite on the composite motor case which fabricated by filament winding process. We also consider the importance of the requirement analysis for effective, successful system development under given system conditions. In order to develop the basic requirement analysis for the thermal protective cork-based exterior insulator, an experimental requirement analysis was accomplished, and some experimental comparing results, the study for preventing fungi are presented.